Yields hybrid corn

An ear of modern corn. Modern hybrid corn produces several ears each bearing in excess of 1000 kernels. The major difference between these two plants is that modern corn is much more productive and more nutritious. If humans had to depend on the wild relative alone, hundreds, if not thousands, of times more plants would be needed. That in turn would take hundreds or thousands of times more acres, in order to get the same yield. (University of California Division of Agricultural and Natural Resources Statewide Biotechnology Workgroup, 2007)... 

Classical breeding has been the mainstay of crop improvement since the rediscovery of Mendelian genetics at the beginning of this century. The improvements have been significant, e.g., the development of hybrid corn resulted in a steady 1-2% increase in yield per year. Other crop breeding programs led to the development of strains that would sustain food production in previously sterile environments. ... 

By the 1970s production techniques had been mastered, seed quality had improved, and simpler hybrids allowed a more reasonable seed price. In addition, fertilizer use increased and irrigation became more sophisticated. Yields increased (Figure 5.3) and the area under cultivation rose dramatically. By 1972, there were 1 800 000 ha of grain corn, and by 1983, there were 1 400 000 ha of com silage. These areas of production have since remained relatively static - primarily as a result of international competition and the resulting fall in prices. 

The average oil content of commercial com hybrids planted in the com belt has declined over the last 50 years from 4.8-5.0% to 4.4%.52 The apparent cause of this decline has been widespread use of one or two high yielding, low oil content corn inbreds. At the same time, the iodine value of com oil has increased from 122-124 to 128-130, equivalent to a linoleic acid content increase from 55% to 60%. This change is apparently associated with the decline in oil content.53... 

Figure 9.4 Starch yield frequency distribution for 131 corn samples representing the range of commercially available hybrids in the central Illinois area.

Singh, V., and Graeber, J. V. 2005. Effect of corn hybrid variability and planting location on ethanol yields. Trans. ASAE, 48,709-714. 

Close coordination between the seed company and the chemical company is essential to assure that yield trials, efficacy trials, hybrid seed production, and the required herbicide label extensions proceed in a concerted fashion. The imidazolinone herbicide must be ready to be used when imidazolinone-resistant corn is ready for sale. Joint launch of the resistant hybrids and the herbicide label extension that includes resistant com will be coordinated by American Cyanamid and Pioneer Hi-Bred. 

Since the 1930 s, the rapid adoption of hybrid seed corn has fueled the development of the seed industry. Hybrid sales rose on the same traj ectory as corn yields to around a billion dollars today. Because the offspring of hybrid seed are not reliable, farmers were guaranteed to be repeat customers and profits flowed steadily to the seed industry. As Kloppenburg (33) notes, the sustained profitability of seed companies had brought most of the seed industry into multinational petrochemical and pharmaceutical corporations. Only Pioneer-Hybrid remains an Independent firm. 

The characteristics of these cooked viscous solutions vary from starch to starch. After cooling to room temperature, the starch from roots are clearer and more fluid, while starch from the cereal grains yield a cloudy less fluid paste that tends to be jellylike. These characteristics are dependent upon the amylose and amylopectin content of the starch and upon the size of the amylose and amylopectin molecule. Some hybrids—waxy hybrids—of corn and sorghum have been developed which yield starch that is almost entirely amylopectin, while other hybrids have a high amylose content. Overall, the tendency to thicken or gel upon cooling, and to become opaque is caused by the presence of amylose. 

Figure 9.3 Seasonal variation in ethanol yields from commodity com (mixture of several hybrids stored in ambient conditions) and control corn (single hybrid stored at 4°C) with...

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